5a Food Production

a) Food production

Students will be assessed on their ability to:

Crop plants

5.1 describe how glasshouses and polythene tunnels can be used to increase the yield of certain crops

- Prevents frost from forming

- Retains heat

- Prevents low humidity levels (prevents water loss)

- Prevents

5.2 understand the effects on crop yield of increased carbon dioxide and increased temperature in glasshouses

Increasing CO2 -> Increases the amount of substrate, therefore more products from photosynthesis, resulting in higher yield

Increasing temperature -> increases the rate of reaction (provided it is not already past optimum temp. of enzymes) and therefore more yield

-> Glasshouses allow both these factors to be controlled = highest yield

5.3 understand the use of fertiliser to increase crop yield

Fertilisers consists of NITRATES AND/OR PHOSPHATES; these help promote growth and increase crop yield

Nitrates -> For amino acids/protein

Phosphates -> DNA/Membrane structure

There are two commonly found types:

Organic

-       Animal waster (i.e. cow dung)

-       These are left to ferment and decompose

-       This results in manure - fertiliser

Inorganic (artificially synthesised)

- Correct amounts of Potassium Nitrate and Ammonium Nitrate are added into a solution, which releases them

5.4 understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants

Monoculture = a field of crops consisting of only one type of crop – these are VERY SUSCEPTIBLE to pests and pesticides (chemicals) which kill and ward off these pests are used

PESTICIDES

Advantages

-       Easy to obtain

-       Effective

-       Easy to spray onto crops

Disadvantages

-       Toxic to both animals and dangerous to humans in large amounts

-       Bioaccumulation is when this toxicity is transferred throughout the food chain

-       Mutation in pests leads to resistance to pesticides

BIOLOGICAL CONTROL

When an alien species (from another ecological system) is introduced; higher in the food chain -> eats pests

Advantages

-       Non-toxic

-       Less direct impact on plant and animal life

Disadvantages

-       Not 100% effective (could find other prey)

-       Difficult to control alien

-       Once pests are gone, aliens might cause own problems

 Microorganisms

5.5 understand the role of yeast in the production of beer

1.    Starch from grains (i.e. Barley)

2.    Starch (polysaccharide) --- Malting (maltose/amylase) -à Glucose

3.    Anaerobic respiration (fermentation)

Glucose --- enzymes (from yeast) --à Ethanol + Carbon Dioxide

4.    Hops from flowers are added to Ethanol for flavor

5.6 describe a simple experiment to investigate carbon dioxide production by yeast, in different conditions

5.7 understand the role of bacteria (Lactobacillus) in the production of yoghurt

1.    Harmful bacteria removed from cow milk by pasteurization

2.    Milk sugars (lactose) are converted into lactic acid

-       45 - 46°C = Optimum temperature

-       Lactobacillus produces enzymes which converts

3.    Acidic conditions stimulate the solidification of the milk

4.    Solidified milk = yoghurt

5.8 interpret and label a diagram of an industrial fermenter and explain the need to provide suitable conditions in the fermenter, including aseptic precautions, nutrients, optimum temperature and pH, oxygenation and agitation, for the growth of microorganisms

Fermentation occurs in the fermenter = its goal is to provide the optimum conditions for fermentation in the following ways:

Aseptic Precautions  = this prevents pathogens and unwanted bacteria from contaminating the substrates and products

Optimum temperature = enzymes produced by the microorganism function best at this temperature, so to produce more yield, this temperature is controlled

pH Levels = enzymes also function best at a certain pH, so this is similarly controlled by the fermenter

Oxygenation = Oxygen is needed in the reaction since it is aerobic

Agitation = this ensures that the microorganisms are distributed evenly throughout the fermenter, and prevents clusters of them from forming; also ensures even temperature and nutrient concentration

Fish farming

5.9 explain the methods which are used to farm large numbers of fish to provide a source of protein, including maintenance of water quality, control of intraspecific and interspecific predation, control of disease, removal of waste products, quality and frequency of feeding and the use of selective breeding.

The advantages of eating and breeding fish are as follows:

-       High source of protein

-       Low fat content

-       Fish are efficient at converting nutrients into biomass

By fish farming, we increase the yield of fish and fish mass produced:

-       Water quality can be controlled

-       Predators can be removed

-       Disease can be controlled (through anti-biotics)

-       Other pests can be controlled

Note that the higher the density of fish, the higher the chance that disease will spread. Farmers control this by use of antibiotics and pesticides (to keep away pathogen carrying pests) – the disadvantages of this are discussed above.